In various of existing display devices, since an organic light-emitting diode (OLED) display has lighter and thinner appearance design, wider viewing angle and faster response speed and lower power consumption or the like compared with a cathode ray tube (CRT) display or a thin film transistor liquid crystal display (TFT-LCD), the OLED display has gradually become the next generation display device and has attracted considerable attention.
The OLED display device is a self-luminous device, which usually comprises a pixel electrode, a counter electrode opposite to the pixel electrode and an organic light-emitting layer between the pixel electrode and the counter electrode. The OLED display device applies a voltage to the pixel electrode and the counter electrode so as to form an electric field across the organic light-emitting layer between the pixel electrode and the counter electrode, thereby electrons and holes in the organic light-emitting layer can combine with each other for luminescence. An array substrate having circuit unit is used to control the voltage applied to the pixel electrode, thereby to control the display effect of the OLED display device.